The /var/lib/containerd/io.containerd.grpc.v1.introspection/uuid file
stores a UUID to identify the particular containerd daemon responding to
requests. The file should either exist with a UUID, or not exist.
However, it has been observed that the file can be truncated with 0
bytes, which will then fail to be parsed as a valid UUID.
As a defensive practice, detect a 0-length file and overwrite with a new
UUID rather than failing.
Fixes: https://github.com/containerd/containerd/issues/10491
Signed-off-by: Samuel Karp <samuelkarp@google.com>
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